WASHINGTON -- The Obama administration announced Wednesday a $1.83 billion arms sale to Taiwan, the first offered by the U.S. to the self-governing island in four years.

China regards Taiwan as part of its territory and has said the sale, which was expected, should be canceled to avoid harming its relations across the Taiwan Strait and between China and the U.S.

The administration notified Congress that the proposed arms package includes two decommissioned U.S. Navy frigates, anti-tank missiles, amphibious assault vehicles, and Stinger surface-to-air missiles. There's also support for Taiwan's capabilities in intelligence, surveillance and reconnaissance and a weapons system to defend against anti-ship missiles.

Congress has 30 days to review the sale, but it's unlikely to raise objections. There's been mounting bipartisan concern that Taiwan is inadequately armed to defend itself against an increasingly powerful mainland China.

David McKeeby, a State Department spokesman on political-military affairs, said the package is consistent with U.S. support for Taiwan's ability to defend itself under the Taiwan Relations Act.

Republican lawmakers quickly welcomed the announcement, but called for more frequent arms sales to Taiwan.

"I remain deeply concerned about the administration's delays that needlessly dragged out this process," said Rep. Ed Royce, chairman of the House Foreign Affairs Committee. "In fact, some Taiwanese requests have still not seen the light of day. We should handle arms transfers for Taiwan just as we would for any other close security partner."

Sen. John McCain, chairman of the Senate Armed Services Committee, said the U.S. must establish a more regularized process for considering Taiwan requests, "in order to avoid extended periods in which a fear of upsetting the U.S.-China relationship may harm Taiwan's defense capabilities."

The administration has announced more than $12 billion in arms sales to Taiwan since 2010, but none since $5.9 billion in sales in September 2011 that included upgrades for Taiwan's F-16 fighter jets. That drew a diplomatic protest from Beijing, which suspended some military exchanges with the United States. It did not seriously impair ties.

President Barack Obama has sought greater cooperation with China on issues such as climate change, and the two sides have increased military exchanges to reduce the risk of conflict. But at the same time, relations have been roiled by China's construction of artificial islands in the South China Sea and allegations of Chinese cyber theft.

In Beijing on Tuesday, China's Foreign Ministry issued a stern warning that the sale threatened relations with the U.S.

On Wednesday, Ma Xiaoguang, China's spokesman for the Cabinet's Taiwan Affairs Office, reiterated China's opposition to arms sales to Taiwan from any country and called for Taiwan to "treasure" improved relations with the mainland.

Relations across the Taiwan Strait have undergone a steady improvement over the past two decades, especially under the China-friendly administration of Taiwanese President Ma Ying-jeou.